Analysis of Residual Stress Development during Thermal Processing of AL-SI Alloys

2011 ◽  
Vol 681 ◽  
pp. 358-363
Author(s):  
S. Mohsen Sadrossadat ◽  
Ru Lin Peng ◽  
Sten Johansson
Keyword(s):  
Heat Treatment ◽  
Thermal Analysis ◽  
Residual Stress ◽  
Residual Stresses ◽  
Water Flow ◽  
Stress Measurement ◽  
Cooling Water ◽  
Base Temperature ◽  
Thermal Treatments ◽  
Thermal Residual Stresses

Residuals stresses can be present in almost every industrial component. Manufacturing processes such as casting, welding, and heat treatment are the most common causes of residual stresses. Thermal residual stresses could be developed in a component during heat treatment process as a result of non-uniform heating or cooling operations. In this study, experiments were carried out to develop insights into and understanding of the residual stresses that can arise during thermal treatments of Al-Si components. Due to the complexity of residual stresses analysis in real components, a common mixed-section casting was employed. In order to fulfill the requirements of performing different thermal treatments, a special cooling apparatus was designed and built. A number of the casting components of an Al-Si alloy were annealed for stress relief, and then removed from the furnace and cooled with different water flow rates. Then, the amount of accumulated residual stresses in the components was measured relaxation of stress using cutting. Thermal analysis and residual stress measurement for different thermal treatment regimes showed that by choosing a specific holding temperature before direct cooling, the value of residual stress increases linearly with flow rate of cooling. On the other hand, for a constant value of cooling water flow, ∆Tmaxand residual stress level decreases when the value of base temperature of furnace decreases. Moreover, the cutting method can be a suitable method for measuring thermal residual stresses in Al-Si components and thermal analysis is a powerful technique to predict residual stresses.

scholarly journals Residual Stress Measurement in Heat Treated Cylindrical Components

2021 ◽  
Author(s):  
M. Belassel ◽  
J. Pineault ◽  
M. Bolla ◽  
M. Brauss
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Residual Stresses ◽  
Stress Measurement ◽  
Microstructural Characterization ◽  
Plain Carbon Steel ◽  
X Ray Diffraction ◽  
Treatment Processes ◽  
Heat Treated ◽  
Xrd Techniques

Abstract Heat treatment processes can generate steep residual stress (RS) gradients and plastic deformation in metal components due to differential cooling and other effect such as phase transformation. The magnitude of residual stresses generated, and how quickly they vary spatially, will depend upon the material itself and the temperature gradients introduced during the heat treatment process. X-ray diffraction (XRD) techniques can be used to characterize residual stresses, as well as microstructural changes, including dislocation density and particle size in heat treated components. Plain carbon steel cylinders were heat treated, quenched and characterized using these methods. Residual stress measurements were performed via XRD using the Sin2Ψ technique and microstructural characterization was evaluated using the associated peak widths. Measurements were carried out both at the surface and through depth using electropolishing. The results indicate triaxial stress gradients exist in all samples investigated, with concomitant varying microstructural characteristics.

scholarly journals Residual Stress State of X65 Pipeline Girth Welds Before and After Local and Furnace Post Weld Heat Treatment

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Yao Ren ◽  
Anna Paradowska ◽  
Bin Wang ◽  
Elvin Eren ◽  
Yin Jin Janin
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Residual Stresses ◽  
Outer Surface ◽  
Post Weld Heat Treatment ◽  
Pipe Length ◽  
Stress Profiles ◽  
Girth Welds ◽  
Welded Pipe ◽  
Weld Heat

This research investigated the effects of global (in other words, furnace-based) and local post weld heat treatment (PWHT) on residual stress (RS) relaxation in API 5L X65 pipe girth welds. All pipe spools were fabricated using identical pipeline production procedures for manufacturing multipass narrow gap welds. Nondestructive neutron diffraction (ND) strain scanning was carried out on girth welded pipe spools and strain-free comb samples for the determination of the lattice spacing. All residual stress measurements were carried out at the KOWARI strain scanning instrument at the Australian Nuclear Science and Technology Organization (ANSTO). Residual stresses were measured on two pipe spools in as-welded condition and two pipe spools after local and furnace PWHT. Measurements were conducted through the thickness in the weld material and adjacent parent metal starting from the weld toes. Besides, three line-scans along pipe length were made 3 mm below outer surface, at pipe wall midthickness, and 3 mm above the inner surface. PWHT was carried out for stress relief; one pipe was conventionally heat treated entirely in an enclosed furnace, and the other was locally heated by a flexible ceramic heating pad. Residual stresses measured after PWHT were at exactly the same locations as those in as-welded condition. Residual stress states of the pipe spools in as-welded condition and after PWHT were compared, and the results were presented in full stress maps. Additionally, through-thickness residual stress profiles and the results of one line scan (3 mm below outer surface) were compared with the respective residual stress profiles advised in British Standard BS 7910 “Guide to methods for assessing the acceptability of flaws in metallic structures” and the UK nuclear industry's R6 procedure. The residual stress profiles in as-welded condition were similar. With the given parameters, local PWHT has effectively reduced residual stresses in the pipe spool to such a level that it prompted the thought that local PWHT can be considered a substitute for global PWHT.

scholarly journals Cross-Sectional Mapping of Residual Stresses by Measuring the Surface Contour After a Cut

2000 ◽  
Vol 123 (2) ◽  
pp. 162-168 ◽  
Author(s):  
M. B. Prime
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Stress Measurement ◽  
Superposition Principle ◽  
New Method ◽  
Contour Method ◽  
Stress Profile ◽  
Relaxation Methods ◽  
Cross Sectional ◽  
Residual Stress Profile

A powerful new method for residual stress measurement is presented. A part is cut in two, and the contour, or profile, of the resulting new surface is measured to determine the displacements caused by release of the residual stresses. Analytically, for example using a finite element model, the opposite of the measured contour is applied to the surface as a displacement boundary condition. By Bueckner’s superposition principle, this calculation gives the original residual stresses normal to the plane of the cut. This “contour method” is more powerful than other relaxation methods because it can determine an arbitrary cross-sectional area map of residual stress, yet more simple because the stresses can be determined directly from the data without a tedious inversion technique. The new method is verified with a numerical simulation, then experimentally validated on a steel beam with a known residual stress profile.

Effect of Thermal Residual Stresses on Polymer/Metal Interfacial Adhesion

1999 ◽  
Author(s):  
Qizhou Yao ◽  
Jianmin Qu
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Coefficient Of Thermal Expansion ◽  
Interfacial Crack ◽  
Thermal Residual Stress ◽  
Element Analysis ◽  
Thermal Residual Stresses ◽  
Interfacial Cracks ◽  
Cte Mismatch ◽  
Elastic Mismatch

Abstract In this study, the apparent fracture toughness of the interfaces of several epoxy-based polymeric adhesives and metal (aluminum) substrate is experimentally measured. Double layer specimens with initial interfacial cracks are made for four-point bending tests. Thermal residual stresses exist on the interface due to the coefficient of thermal expansion (CTE) mismatch between the underfill and aluminum. Silica fillers are used to modify the CTE of the epoxy-based adhesives so that various levels of interface thermal residual stresses are achieved. Finite element analysis is also performed to quantify the effects of CTE mismatch as well as the elastic mismatch across the interface. It is found that the apparent interfacial toughness is significantly affected by the thermal residual stress, while the effect of elastic mismatch is negligible. In general thermal residual stress undermines the resistance to an interfacial crack. In some cases the residual stress is sufficient to result in adhesive and/or cohesive failure.

scholarly journals UK Research Programme on Residual Stresses: A Review of Progress

2008 ◽  
Author(s):  
S. K. Bate ◽  
P. Hurrell ◽  
J. A. Francis ◽  
M. Turski
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Stress Measurement ◽  
Experimental Testing ◽  
Research Programme ◽  
Austenitic Steels ◽  
Assessment Procedure ◽  
Engineering Structures ◽  
Modelling Techniques

A long-term UK research programme on residual stresses was launched in 2004. It involves Rolls-Royce plc and Serco Assurance, supported by UK industry and academia. The programme is aimed at progressing the understanding of weld residual stresses and the implementation of finite element simulation and residual stress measurement for assessing the integrity of engineering structures. Following on from this, the intention is then to develop improved guidance on residual stress modelling techniques and then to provide methods and analysis tools for design in order to control and minimise residual stress. The focus of the work to date has been to develop modelling guidelines which can be used by a finite element analyst to predict the residual stresses in austenitic welded components. These guidelines are now drafted and will be incorporated into the next issue of the British Energy R6 defect assessment procedure following peer review. The guidelines have been developed based on the experience that has been attained using various modelling techniques. To support this development, a series of welded mock-ups have been manufactured. The residual stresses in these welds have been measured using various techniques (diffraction and strain relaxation). These measurements are being used to validate the predicted stresses. It is only by corroborating each other that the resulting residual stresses can be confidently used for assessment. Mock-ups are also being used to develop material models for ferritic steel which undergo phase transformations, and to investigate how various weld parameters affect the magnitude and distribution of residual stress. Similarly, mock-ups have been manufactured to investigate the effect of start-stops on residual stresses. The programme is also supported by experimental testing to develop physical and mechanical properties which are required for analysis, i.e. up to melting temperature. Both conventional and miniaturised testing has been used to measure properties in ferritic and austenitic steels. A task has also been undertaken to develop a methodology for providing upper bound residual stress profiles which can be used as an initial estimate of stress for use in structural assessment.

UK Research Programme on Residual Stresses: Progress to Date

2007 ◽  
Author(s):  
S. K. Bate ◽  
A. P. Warren ◽  
C. T. Watson ◽  
P. Hurrell ◽  
J. A. Francis
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Stress Measurement ◽  
Research Programme ◽  
Assessment Procedure ◽  
Engineering Structures ◽  
Element Analysis ◽  
Simplifying Assumptions ◽  
Modelling Techniques

A long-term UK research programme on residual stresses was launched in 2004. It involves Rolls-Royce plc and Serco Assurance, and is supported by UK industry and academia. The programme is aimed at progressing the understanding of weld residual stresses and the implementation of finite element simulation and residual stress measurement for assessing the integrity of engineering structures. Following on from this, the intention is then to develop improved guidance on residual stress modelling techniques. In the first two years finite element activities have addressed heat source representation, simplified modelling (e.g. 2D v 3D, bead lumping), material hardening models, high temperature behaviour and phase transformations. It is recognized that simplifying assumptions have to be made in order to reduce the computational run-time and modelling complexity, especially for multi-pass welds. The effects of these assumptions on the determined stresses have been considered by carrying out finite element analyses of welded mock-ups. The welded mock-ups have been developed to provide measured residual stress data which are necessary to validate the modelling techniques that have been developed. These activities have been used to support the development of guidelines on the use finite element analysis to predict residual stresses in welded components. These guidelines will be incorporated in the next issue of the British Energy R6 defect assessment procedure.

Relationship Between Forced Vibration Method and Residual Stress in Die Materials

2020 ◽  
Vol 14 (5) ◽  
pp. 824-834
Author(s):  
Masashi Kurose ◽  
Hiromasa Anahara ◽  
Takeshi Tane ◽  
Yoshihide Kuwabara ◽  
Kenta Aoshima ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Stress Reduction ◽  
Forced Vibration ◽  
Stress Measurement ◽  
Die Casting ◽  
Tensile Residual Stress ◽  
Cavity Surface ◽  
Repeated Heating ◽  
Die Materials

During aluminum die-casting, tensile residual stress accumulates on the cavity surface of the die by repeated heating and cooling processes. Recently, to improve productivity, dies with high cycle and longer life have become necessary, and reduction or removal of tensile residual stress can be used to prevent heat cracks that cause mold fracture. Heat treatment is often used for residual stress reduction but a more efficient residual stress reduction method that can be carried out with simpler equipment is required. In this study, the relationship between the residual stress after forced vibration and the amplitude at the time of excitation is investigated by mechanical vibration of the SKD61 die materials and the die-casting mold through the application of forced vibration by an eccentric motor. Residual stress on the surface of each test plate treated by the heat treatment and the surface of mold cavity after excitation is evaluated by the X-ray residual stress measurement. It was found that the residual strain after excitation accumulated in compression as the amplitude of oscillation of the specimen became negative. Residual stress in the excitation direction of the specimens increased in the compression direction due to the excitation, demonstrating the effective stress reduction by the excitation method.

Research on the Residual Stresses in Cold-Formed Hat-Shaped Section

2012 ◽  
Vol 204-208 ◽  
pp. 934-938
Author(s):  
Hua Chen Liu ◽  
Feng Zhao
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Cutting Tool ◽  
Electrical Discharge Machining ◽  
Stress Measurement ◽  
Strain Gauges ◽  
Test Results ◽  
Antiseptic Treatment ◽  
Experimental Findings ◽  
Shaped Section

In the paper,the electrical discharge machining(EDM) technique was used to cut strips for cold-formed residual stress measurement of hat-shaped section.After adjusting the electrolyte ratio,designing specific the cutting tool and improving the methodof antiseptic treatment,the test results improved significantly. Electrical resistance strain gauges with EDM cutting technique were used to establish the magnitude and distribution of the residual stresses in cold-formed hat-shaped section.Based on the experimental findings, an idealized distribution pattern of the residual stress in cold-formed hat-shaped section is presented.

Evaluation of Welding Residual Stresses in Power Plant Facilities by Using a Newly Developed Indentation Technique

2002 ◽  
Author(s):  
Jae-il Jang ◽  
Dongil Son ◽  
Yeol Choi ◽  
Yun-Hee Lee ◽  
Won-Jae Ji ◽  
...  
Keyword(s):  
Residual Stress ◽  
Power Plant ◽  
Residual Stresses ◽  
Stress Measurement ◽  
Welding Residual Stress ◽  
Large Scatter ◽  
Indentation Technique ◽  
Cutting Test ◽  
Non Destructive ◽  
Non Destructive Techniques

It is well known that residual stress is one of the important problems in welding design/fabrications and sound maintenance of welded structures. Thus, the demand for quantitative evaluation of welding residual stress has been increased. However, conventional non-destructive techniques for welding residual stress measurement have many difficulties in in-field applications according to poor repeatability, large scatter of obtained data, complex procedures, inaccurate results, and etc. To overcome these difficulties, a newly developed indentation technique was proposed in this study, and applied to evaluate the welding residual stress in electric power plant facilities. By comparing with the stress values obtained from the destructive saw-cutting test, it could be concluded that the new indentation technique is very useful for quantitative/non-destructive evaluation of welding residual stresses in industrial fields such as power plant facilities.

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